#region Copyright & License

//
// Copyright 2001-2006 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

using System;
using System.Reflection;
using log4net.Core;

namespace log4net {
  /// <summary>
  /// The ILog interface is use by application to log messages into
  /// the log4net framework.
  /// </summary>
  /// <remarks>
  /// <para>
  /// Use the <see cref="LogManager"/> to obtain logger instances
  /// that implement this interface. The <see cref="LogManager.GetLogger(Assembly,Type)"/>
  /// static method is used to get logger instances.
  /// </para>
  /// <para>
  /// This class contains methods for logging at different levels and also
  /// has properties for determining if those logging levels are
  /// enabled in the current configuration.
  /// </para>
  /// <para>
  /// This interface can be implemented in different ways. This documentation
  /// specifies reasonable behavior that a caller can expect from the actual
  /// implementation, however different implementations reserve the right to
  /// do things differently.
  /// </para>
  /// </remarks>
  /// <example>Simple example of logging messages
  /// <code lang="C#">
  /// ILog log = LogManager.GetLogger("application-log");
  /// 
  /// log.Info("Application Start");
  /// log.Debug("This is a debug message");
  /// 
  /// if (log.IsDebugEnabled)
  /// {
  ///		log.Debug("This is another debug message");
  /// }
  /// </code>
  /// </example>
  /// <seealso cref="LogManager"/>
  /// <seealso cref="LogManager.GetLogger(Assembly, Type)"/>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  public interface ILog : ILoggerWrapper {
    /// <summary>
    /// Checks if this logger is enabled for the <see cref="Level.Debug"/> level.
    /// </summary>
    /// <value>
    /// <c>true</c> if this logger is enabled for <see cref="Level.Debug"/> events, <c>false</c> otherwise.
    /// </value>
    /// <remarks>
    /// <para>
    /// This function is intended to lessen the computational cost of
    /// disabled log debug statements.
    /// </para>
    /// <para> For some ILog interface <c>log</c>, when you write:</para>
    /// <code lang="C#">
    /// log.Debug("This is entry number: " + i );
    /// </code>
    /// <para>
    /// You incur the cost constructing the message, string construction and concatenation in
    /// this case, regardless of whether the message is logged or not.
    /// </para>
    /// <para>
    /// If you are worried about speed (who isn't), then you should write:
    /// </para>
    /// <code lang="C#">
    /// if (log.IsDebugEnabled)
    /// { 
    ///     log.Debug("This is entry number: " + i );
    /// }
    /// </code>
    /// <para>
    /// This way you will not incur the cost of parameter
    /// construction if debugging is disabled for <c>log</c>. On
    /// the other hand, if the <c>log</c> is debug enabled, you
    /// will incur the cost of evaluating whether the logger is debug
    /// enabled twice. Once in <see cref="IsDebugEnabled"/> and once in
    /// the <see cref="Debug(object)"/>.  This is an insignificant overhead
    /// since evaluating a logger takes about 1% of the time it
    /// takes to actually log. This is the preferred style of logging.
    /// </para>
    /// <para>Alternatively if your logger is available statically then the is debug
    /// enabled state can be stored in a static variable like this:
    /// </para>
    /// <code lang="C#">
    /// private static readonly bool isDebugEnabled = log.IsDebugEnabled;
    /// </code>
    /// <para>
    /// Then when you come to log you can write:
    /// </para>
    /// <code lang="C#">
    /// if (isDebugEnabled)
    /// { 
    ///     log.Debug("This is entry number: " + i );
    /// }
    /// </code>
    /// <para>
    /// This way the debug enabled state is only queried once
    /// when the class is loaded. Using a <c>private static readonly</c>
    /// variable is the most efficient because it is a run time constant
    /// and can be heavily optimized by the JIT compiler.
    /// </para>
    /// <para>
    /// Of course if you use a static readonly variable to
    /// hold the enabled state of the logger then you cannot
    /// change the enabled state at runtime to vary the logging
    /// that is produced. You have to decide if you need absolute
    /// speed or runtime flexibility.
    /// </para>
    /// </remarks>
    /// <seealso cref="Debug(object)"/>
    /// <seealso cref="DebugFormat(IFormatProvider, string, object[])"/>
    bool IsDebugEnabled { get; }

    /// <summary>
    /// Checks if this logger is enabled for the <see cref="Level.Info"/> level.
    /// </summary>
    /// <value>
    /// <c>true</c> if this logger is enabled for <see cref="Level.Info"/> events, <c>false</c> otherwise.
    /// </value>
    /// <remarks>
    /// For more information see <see cref="ILog.IsDebugEnabled"/>.
    /// </remarks>
    /// <seealso cref="Info(object)"/>
    /// <seealso cref="InfoFormat(IFormatProvider, string, object[])"/>
    /// <seealso cref="ILog.IsDebugEnabled"/>
    bool IsInfoEnabled { get; }

    /// <summary>
    /// Checks if this logger is enabled for the <see cref="Level.Warn"/> level.
    /// </summary>
    /// <value>
    /// <c>true</c> if this logger is enabled for <see cref="Level.Warn"/> events, <c>false</c> otherwise.
    /// </value>
    /// <remarks>
    /// For more information see <see cref="ILog.IsDebugEnabled"/>.
    /// </remarks>
    /// <seealso cref="Warn(object)"/>
    /// <seealso cref="WarnFormat(IFormatProvider, string, object[])"/>
    /// <seealso cref="ILog.IsDebugEnabled"/>
    bool IsWarnEnabled { get; }

    /// <summary>
    /// Checks if this logger is enabled for the <see cref="Level.Error"/> level.
    /// </summary>
    /// <value>
    /// <c>true</c> if this logger is enabled for <see cref="Level.Error"/> events, <c>false</c> otherwise.
    /// </value>
    /// <remarks>
    /// For more information see <see cref="ILog.IsDebugEnabled"/>.
    /// </remarks>
    /// <seealso cref="Error(object)"/>
    /// <seealso cref="ErrorFormat(IFormatProvider, string, object[])"/>
    /// <seealso cref="ILog.IsDebugEnabled"/>
    bool IsErrorEnabled { get; }

    /// <summary>
    /// Checks if this logger is enabled for the <see cref="Level.Fatal"/> level.
    /// </summary>
    /// <value>
    /// <c>true</c> if this logger is enabled for <see cref="Level.Fatal"/> events, <c>false</c> otherwise.
    /// </value>
    /// <remarks>
    /// For more information see <see cref="ILog.IsDebugEnabled"/>.
    /// </remarks>
    /// <seealso cref="Fatal(object)"/>
    /// <seealso cref="FatalFormat(IFormatProvider, string, object[])"/>
    /// <seealso cref="ILog.IsDebugEnabled"/>
    bool IsFatalEnabled { get; }

    /// <overloads>Log a message object with the <see cref="Level.Debug"/> level.</overloads>
    /// <summary>
    /// Log a message object with the <see cref="Level.Debug"/> level.
    /// </summary>
    /// <param name="message">The message object to log.</param>
    /// <remarks>
    /// <para>
    /// This method first checks if this logger is <c>DEBUG</c>
    /// enabled by comparing the level of this logger with the 
    /// <see cref="Level.Debug"/> level. If this logger is
    /// <c>DEBUG</c> enabled, then it converts the message object
    /// (passed as parameter) to a string by invoking the appropriate
    /// <see cref="log4net.ObjectRenderer.IObjectRenderer"/>. It then 
    /// proceeds to call all the registered appenders in this logger 
    /// and also higher in the hierarchy depending on the value of 
    /// the additivity flag.
    /// </para>
    /// <para><b>WARNING</b> Note that passing an <see cref="Exception"/> 
    /// to this method will print the name of the <see cref="Exception"/> 
    /// but no stack trace. To print a stack trace use the 
    /// <see cref="Debug(object,Exception)"/> form instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Debug(object,Exception)"/>
    /// <seealso cref="IsDebugEnabled"/>
    void Debug(object message);

    /// <summary>
    /// Log a message object with the <see cref="Level.Debug"/> level including
    /// the stack trace of the <see cref="Exception"/> passed
    /// as a parameter.
    /// </summary>
    /// <param name="message">The message object to log.</param>
    /// <param name="exception">The exception to log, including its stack trace.</param>
    /// <remarks>
    /// <para>
    /// See the <see cref="Debug(object)"/> form for more detailed information.
    /// </para>
    /// </remarks>
    /// <seealso cref="Debug(object)"/>
    /// <seealso cref="IsDebugEnabled"/>
    void Debug(object message, Exception exception);

    /// <overloads>Log a formatted string with the <see cref="Level.Debug"/> level.</overloads>
    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Debug"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Debug(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Debug(object)"/>
    /// <seealso cref="IsDebugEnabled"/>
    void DebugFormat(string format, params object[] args);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Debug"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Debug(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Debug(object)"/>
    /// <seealso cref="IsDebugEnabled"/>
    void DebugFormat(string format, object arg0);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Debug"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Debug(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Debug(object)"/>
    /// <seealso cref="IsDebugEnabled"/>
    void DebugFormat(string format, object arg0, object arg1);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Debug"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <param name="arg2">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Debug(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Debug(object)"/>
    /// <seealso cref="IsDebugEnabled"/>
    void DebugFormat(string format, object arg0, object arg1, object arg2);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Debug"/> level.
    /// </summary>
    /// <param name="provider">An <see cref="IFormatProvider"/> that supplies culture-specific formatting information</param>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Debug(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Debug(object)"/>
    /// <seealso cref="IsDebugEnabled"/>
    void DebugFormat(IFormatProvider provider, string format, params object[] args);

    /// <overloads>Log a message object with the <see cref="Level.Info"/> level.</overloads>
    /// <summary>
    /// Logs a message object with the <see cref="Level.Info"/> level.
    /// </summary>
    /// <remarks>
    /// <para>
    /// This method first checks if this logger is <c>INFO</c>
    /// enabled by comparing the level of this logger with the 
    /// <see cref="Level.Info"/> level. If this logger is
    /// <c>INFO</c> enabled, then it converts the message object
    /// (passed as parameter) to a string by invoking the appropriate
    /// <see cref="log4net.ObjectRenderer.IObjectRenderer"/>. It then 
    /// proceeds to call all the registered appenders in this logger 
    /// and also higher in the hierarchy depending on the value of the 
    /// additivity flag.
    /// </para>
    /// <para><b>WARNING</b> Note that passing an <see cref="Exception"/> 
    /// to this method will print the name of the <see cref="Exception"/> 
    /// but no stack trace. To print a stack trace use the 
    /// <see cref="Info(object,Exception)"/> form instead.
    /// </para>
    /// </remarks>
    /// <param name="message">The message object to log.</param>
    /// <seealso cref="Info(object,Exception)"/>
    /// <seealso cref="IsInfoEnabled"/>
    void Info(object message);

    /// <summary>
    /// Logs a message object with the <c>INFO</c> level including
    /// the stack trace of the <see cref="Exception"/> passed
    /// as a parameter.
    /// </summary>
    /// <param name="message">The message object to log.</param>
    /// <param name="exception">The exception to log, including its stack trace.</param>
    /// <remarks>
    /// <para>
    /// See the <see cref="Info(object)"/> form for more detailed information.
    /// </para>
    /// </remarks>
    /// <seealso cref="Info(object)"/>
    /// <seealso cref="IsInfoEnabled"/>
    void Info(object message, Exception exception);

    /// <overloads>Log a formatted message string with the <see cref="Level.Info"/> level.</overloads>
    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Info"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Info(object)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Info(object,Exception)"/>
    /// <seealso cref="IsInfoEnabled"/>
    void InfoFormat(string format, params object[] args);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Info"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Info(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Info(object)"/>
    /// <seealso cref="IsInfoEnabled"/>
    void InfoFormat(string format, object arg0);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Info"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Info(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Info(object)"/>
    /// <seealso cref="IsInfoEnabled"/>
    void InfoFormat(string format, object arg0, object arg1);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Info"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <param name="arg2">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Info(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Info(object)"/>
    /// <seealso cref="IsInfoEnabled"/>
    void InfoFormat(string format, object arg0, object arg1, object arg2);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Info"/> level.
    /// </summary>
    /// <param name="provider">An <see cref="IFormatProvider"/> that supplies culture-specific formatting information</param>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Info(object)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Info(object,Exception)"/>
    /// <seealso cref="IsInfoEnabled"/>
    void InfoFormat(IFormatProvider provider, string format, params object[] args);

    /// <overloads>Log a message object with the <see cref="Level.Warn"/> level.</overloads>
    /// <summary>
    /// Log a message object with the <see cref="Level.Warn"/> level.
    /// </summary>
    /// <remarks>
    /// <para>
    /// This method first checks if this logger is <c>WARN</c>
    /// enabled by comparing the level of this logger with the 
    /// <see cref="Level.Warn"/> level. If this logger is
    /// <c>WARN</c> enabled, then it converts the message object
    /// (passed as parameter) to a string by invoking the appropriate
    /// <see cref="log4net.ObjectRenderer.IObjectRenderer"/>. It then 
    /// proceeds to call all the registered appenders in this logger 
    /// and also higher in the hierarchy depending on the value of the 
    /// additivity flag.
    /// </para>
    /// <para><b>WARNING</b> Note that passing an <see cref="Exception"/> 
    /// to this method will print the name of the <see cref="Exception"/> 
    /// but no stack trace. To print a stack trace use the 
    /// <see cref="Warn(object,Exception)"/> form instead.
    /// </para>
    /// </remarks>
    /// <param name="message">The message object to log.</param>
    /// <seealso cref="Warn(object,Exception)"/>
    /// <seealso cref="IsWarnEnabled"/>
    void Warn(object message);

    /// <summary>
    /// Log a message object with the <see cref="Level.Warn"/> level including
    /// the stack trace of the <see cref="Exception"/> passed
    /// as a parameter.
    /// </summary>
    /// <param name="message">The message object to log.</param>
    /// <param name="exception">The exception to log, including its stack trace.</param>
    /// <remarks>
    /// <para>
    /// See the <see cref="Warn(object)"/> form for more detailed information.
    /// </para>
    /// </remarks>
    /// <seealso cref="Warn(object)"/>
    /// <seealso cref="IsWarnEnabled"/>
    void Warn(object message, Exception exception);

    /// <overloads>Log a formatted message string with the <see cref="Level.Warn"/> level.</overloads>
    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Warn"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Warn(object)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Warn(object,Exception)"/>
    /// <seealso cref="IsWarnEnabled"/>
    void WarnFormat(string format, params object[] args);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Warn"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Warn(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Warn(object)"/>
    /// <seealso cref="IsWarnEnabled"/>
    void WarnFormat(string format, object arg0);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Warn"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Warn(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Warn(object)"/>
    /// <seealso cref="IsWarnEnabled"/>
    void WarnFormat(string format, object arg0, object arg1);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Warn"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <param name="arg2">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Warn(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Warn(object)"/>
    /// <seealso cref="IsWarnEnabled"/>
    void WarnFormat(string format, object arg0, object arg1, object arg2);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Warn"/> level.
    /// </summary>
    /// <param name="provider">An <see cref="IFormatProvider"/> that supplies culture-specific formatting information</param>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Warn(object)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Warn(object,Exception)"/>
    /// <seealso cref="IsWarnEnabled"/>
    void WarnFormat(IFormatProvider provider, string format, params object[] args);

    /// <overloads>Log a message object with the <see cref="Level.Error"/> level.</overloads>
    /// <summary>
    /// Logs a message object with the <see cref="Level.Error"/> level.
    /// </summary>
    /// <param name="message">The message object to log.</param>
    /// <remarks>
    /// <para>
    /// This method first checks if this logger is <c>ERROR</c>
    /// enabled by comparing the level of this logger with the 
    /// <see cref="Level.Error"/> level. If this logger is
    /// <c>ERROR</c> enabled, then it converts the message object
    /// (passed as parameter) to a string by invoking the appropriate
    /// <see cref="log4net.ObjectRenderer.IObjectRenderer"/>. It then 
    /// proceeds to call all the registered appenders in this logger 
    /// and also higher in the hierarchy depending on the value of the 
    /// additivity flag.
    /// </para>
    /// <para><b>WARNING</b> Note that passing an <see cref="Exception"/> 
    /// to this method will print the name of the <see cref="Exception"/> 
    /// but no stack trace. To print a stack trace use the 
    /// <see cref="Error(object,Exception)"/> form instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Error(object,Exception)"/>
    /// <seealso cref="IsErrorEnabled"/>
    void Error(object message);

    /// <summary>
    /// Log a message object with the <see cref="Level.Error"/> level including
    /// the stack trace of the <see cref="Exception"/> passed
    /// as a parameter.
    /// </summary>
    /// <param name="message">The message object to log.</param>
    /// <param name="exception">The exception to log, including its stack trace.</param>
    /// <remarks>
    /// <para>
    /// See the <see cref="Error(object)"/> form for more detailed information.
    /// </para>
    /// </remarks>
    /// <seealso cref="Error(object)"/>
    /// <seealso cref="IsErrorEnabled"/>
    void Error(object message, Exception exception);

    /// <overloads>Log a formatted message string with the <see cref="Level.Error"/> level.</overloads>
    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Error"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Error(object)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Error(object,Exception)"/>
    /// <seealso cref="IsErrorEnabled"/>
    void ErrorFormat(string format, params object[] args);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Error"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Error(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Error(object)"/>
    /// <seealso cref="IsErrorEnabled"/>
    void ErrorFormat(string format, object arg0);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Error"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Error(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Error(object)"/>
    /// <seealso cref="IsErrorEnabled"/>
    void ErrorFormat(string format, object arg0, object arg1);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Error"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <param name="arg2">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Error(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Error(object)"/>
    /// <seealso cref="IsErrorEnabled"/>
    void ErrorFormat(string format, object arg0, object arg1, object arg2);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Error"/> level.
    /// </summary>
    /// <param name="provider">An <see cref="IFormatProvider"/> that supplies culture-specific formatting information</param>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Error(object)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Error(object,Exception)"/>
    /// <seealso cref="IsErrorEnabled"/>
    void ErrorFormat(IFormatProvider provider, string format, params object[] args);

    /// <overloads>Log a message object with the <see cref="Level.Fatal"/> level.</overloads>
    /// <summary>
    /// Log a message object with the <see cref="Level.Fatal"/> level.
    /// </summary>
    /// <remarks>
    /// <para>
    /// This method first checks if this logger is <c>FATAL</c>
    /// enabled by comparing the level of this logger with the 
    /// <see cref="Level.Fatal"/> level. If this logger is
    /// <c>FATAL</c> enabled, then it converts the message object
    /// (passed as parameter) to a string by invoking the appropriate
    /// <see cref="log4net.ObjectRenderer.IObjectRenderer"/>. It then 
    /// proceeds to call all the registered appenders in this logger 
    /// and also higher in the hierarchy depending on the value of the 
    /// additivity flag.
    /// </para>
    /// <para><b>WARNING</b> Note that passing an <see cref="Exception"/> 
    /// to this method will print the name of the <see cref="Exception"/> 
    /// but no stack trace. To print a stack trace use the 
    /// <see cref="Fatal(object,Exception)"/> form instead.
    /// </para>
    /// </remarks>
    /// <param name="message">The message object to log.</param>
    /// <seealso cref="Fatal(object,Exception)"/>
    /// <seealso cref="IsFatalEnabled"/>
    void Fatal(object message);

    /// <summary>
    /// Log a message object with the <see cref="Level.Fatal"/> level including
    /// the stack trace of the <see cref="Exception"/> passed
    /// as a parameter.
    /// </summary>
    /// <param name="message">The message object to log.</param>
    /// <param name="exception">The exception to log, including its stack trace.</param>
    /// <remarks>
    /// <para>
    /// See the <see cref="Fatal(object)"/> form for more detailed information.
    /// </para>
    /// </remarks>
    /// <seealso cref="Fatal(object)"/>
    /// <seealso cref="IsFatalEnabled"/>
    void Fatal(object message, Exception exception);

    /// <overloads>Log a formatted message string with the <see cref="Level.Fatal"/> level.</overloads>
    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Fatal"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Fatal(object)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Fatal(object,Exception)"/>
    /// <seealso cref="IsFatalEnabled"/>
    void FatalFormat(string format, params object[] args);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Fatal"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Fatal(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Fatal(object)"/>
    /// <seealso cref="IsFatalEnabled"/>
    void FatalFormat(string format, object arg0);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Fatal"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Fatal(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Fatal(object)"/>
    /// <seealso cref="IsFatalEnabled"/>
    void FatalFormat(string format, object arg0, object arg1);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Fatal"/> level.
    /// </summary>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="arg0">An Object to format</param>
    /// <param name="arg1">An Object to format</param>
    /// <param name="arg2">An Object to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Fatal(object,Exception)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Fatal(object)"/>
    /// <seealso cref="IsFatalEnabled"/>
    void FatalFormat(string format, object arg0, object arg1, object arg2);

    /// <summary>
    /// Logs a formatted message string with the <see cref="Level.Fatal"/> level.
    /// </summary>
    /// <param name="provider">An <see cref="IFormatProvider"/> that supplies culture-specific formatting information</param>
    /// <param name="format">A String containing zero or more format items</param>
    /// <param name="args">An Object array containing zero or more objects to format</param>
    /// <remarks>
    /// <para>
    /// The message is formatted using the <c>String.Format</c> method. See
    /// <see cref="String.Format(string, object[])"/> for details of the syntax of the format string and the behavior
    /// of the formatting.
    /// </para>
    /// <para>
    /// This method does not take an <see cref="Exception"/> object to include in the
    /// log event. To pass an <see cref="Exception"/> use one of the <see cref="Fatal(object)"/>
    /// methods instead.
    /// </para>
    /// </remarks>
    /// <seealso cref="Fatal(object,Exception)"/>
    /// <seealso cref="IsFatalEnabled"/>
    void FatalFormat(IFormatProvider provider, string format, params object[] args);
  }
}